Moving picture decoding device, moving picture decoding method, and program obtaining chrominance values from corresponding luminance values

ABSTRACT

A decoding device includes a transformer sets a decoded luminance component of a prediction target block to the same number of samples as that of the chrominance component corresponding to the decoded luminance component of the prediction target block and generates a luminance reference signal. A specificator specifies luminance pixels having minimum and maximum pixel values of the decoded luminance component adjacent to the decoded luminance component of the prediction target block, respectively, outputs luminance pixel values obtained from specified luminance pixels, and outputs chrominance pixel values from pigment pixels corresponding to the luminance pixels. A derivator derives a linear prediction parameter from the two pixel values and a linear prediction model. A chrominance linear predictor obtains chrominance prediction signal by applying linear prediction model based on the linear prediction parameter to the luminance reference signal. The chrominance prediction and residual signals are summed to generate a reconstructed chrominance signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. application Ser. No.16/981,771 filed Sep. 17, 2020 which is a U.S. National PhaseApplication under 35 U.S.C. § 371 of International Patent ApplicationNo. PCT/JP2019/047852, filed Dec. 6, 2019, which claims priority ofJapanese Patent Application No. 2018-245882, filed Dec. 27, 2018. Theentire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a moving picture decoding device, amoving picture decoding method, and a program.

BACKGROUND

Conventionally, a moving picture encoding method using intra prediction(intra-frame prediction) or inter prediction (inter-frame prediction),transform/quantization of a prediction residual signal, and entropyencoding has been proposed (for example, ITU-T H.265 High EfficiencyVideo Coding).

A moving picture encoding device corresponding to such a moving pictureencoding method firstly divides an input image into a plurality ofblocks, secondly generates a level value by performing transform andquantization on a residual signal that is a difference between an inputimage and an intra prediction image or an inter prediction image individed block units (one or more transform units), and thirdly generatescoded data by entropy encoding the generated level value together withside information (related information such as a prediction mode and amotion vector necessary for reconstructing a pixel value).

On the other hand, a moving picture decoding device corresponding to amoving picture decoding method obtains an output image from coded databy a procedure reverse to the procedure performed by the moving pictureencoding device.

Specifically, such a moving picture decoding device performs inversequantization and inverse transform on the level value obtained from theencoded data to generate a residual signal, and adds the residual signalto the intra prediction image or the inter prediction image to generatea locally decoded image before filtering, uses the locally decoded imagebefore filtering for intra prediction and at the same time, applies anin-loop filter (for example, a deblocking filter) to generate a locallydecoded image after filtering, and accumulates the locally decoded imageafter filtering in a frame buffer. The frame buffer appropriatelysupplies the locally decoded image after filtering to inter prediction.

Note that processing of obtaining the side information and the levelvalue from the encoded data is referred to parse processing, andreconstructing a pixel value using the side information and level valueis referred to decoding processing.

Here, a chrominance intra prediction method among the intra predictionsin the next-generation moving picture encoding method VVC described inVersatile Video Coding (Draft 3)will be described.

The chrominance intra prediction method includes a cross-componentlinear model (CCLM) that linearly predicts a chrominance component froma reconstructed luminance component, in addition to an intra-colorcomponent prediction method similar to a luminance intra predictionmethod. Since the luminance component and the chrominance component havedifferent numbers of samples in the 4:2:0 color format, a luminancepixel corresponding to a chrominance pixel is derived by smoothing asshown in FIG. 6.

Here, a 6-tap filter used for smoothing is as follows.

pDsY[x][y]=(pY[2*x−1][2*y]+pY[2*x−1][2*y+1]+2*pY[2*x][2*y]+2*pY[2*x][2*y+1]+pY[2*x+1][2*y]+pY[2*x+1][2*y+1]+4) >>3  Equation 1

The linear prediction parameters a and b used for the CCLM method arederived as follows by applying a linear prediction model that performs alinear transform from luminance to chrominance for the pixel values ofthe decoded luminance and chrominance adjacent to a prediction targetblock, using the minimum and maximum pixels of luminance. Here, theparameter k is a constant.

diff=(maxY−minY)>>shift

a=((maxC−minC)*LUT(diff))>>shift

b=minC−((a*minY))>>k)   Equation 2

Then, a chrominance component in the prediction target block ispredicted from the luminance component based on the following linearprediction model and the derived linear prediction parameters a and b.

predSamples[x][y]=Clip 1C(((pDsY[x][y]*a)>>k)+b)   Equation 3

Patent Literature 1: JP-A-2014-195142

SUMMARY

However, the next-generation moving picture encoding method VVC has aproblem that a calculation complexity in deriving predictioncoefficients is high.

Specifically, the next-generation moving picture encoding method VVC hasa problem that the number of bits required for the operation is largerthan the number of bits of other processing blocks because a look-uptable constituting a part of the derivation has high accuracy.

In addition, the next-generation moving picture encoding method VVC hasa problem that the obtained predicted value may exceed the range of theinput pixel value because an absolute value of the predictioncoefficient is not limited.

Furthermore, the next-generation moving picture encoding method VVC hasa problem that a smoothing operation is performed on all pixels to becompared even though only two pixels are finally used when a linearmodel is derived.

Therefore, the present invention has been made in view of theabove-described problems, and an object of the present invention is toprovide a moving picture decoding device, a moving picture encodingdevice, a moving picture processing system, a moving picture decodingmethod, and a program capable of reducing a precision (number of bits)of a lookup table and determining the maximum value of an absolute valueof a prediction coefficient to reduce a required calculation precision(number of bits required for calculation) to the same degree as thecalculation precision of an interpolation filter.

In addition, an object of the present invention is to provide a movingpicture decoding device, a moving picture encoding device, a movingpicture processing system, a moving picture decoding method, and aprogram capable of determining pixels whose luminance becomes theminimum value and the maximum value without smoothing and completelyreducing a smoothing operation even though the number of comparisons isdoubled.

The first aspect of the present invention is summarized as a movingpicture decoding device configured to decode encoded data, the movingpicture decoding device including: a decoding unit configured to decodethe encoded data to obtain a chrominance residual signal; a transformunit configured to set a decoded luminance component of a predictiontarget block to the same number of samples as that of the chrominancecomponent corresponding to the decoded luminance component of theprediction target block, and generate a luminance reference signal; aspecification unit configured to specify pixels of luminance having theminimum and maximum pixel values of the decoded luminance componentadjacent to the decoded luminance component of the prediction targetblock, respectively, output luminance pixel values obtained from thespecified pixels of luminance, and output chrominance pixel valuesobtained from pixels of pigment corresponding to the pixels ofluminance; a derivation unit configured to derive a linear predictionparameter from the luminance pixel value, the chrominance pixel value,and a linear prediction model; a chrominance linear prediction unitconfigured to obtain a chrominance prediction signal by applying thelinear prediction model based on the linear prediction parameter to theluminance reference signal; and an addition unit configured to add thechrominance prediction signal and the chrominance residual signal togenerate a reconstructed chrominance signal, wherein the derivation unitis configured to set an upper limit for a magnitude of the linearprediction parameter, and the specification unit is configured to setthe decoded luminance component adjacent to the decoded luminancecomponent of the prediction target block to the same number of samplesas that of the chrominance component corresponding to the decodedluminance component of the prediction target block, and specify thepixels having the minimum and maximum values of the luminance component,respectively.

The second aspect of the present invention is summarized as a movingpicture decoding method for decoding encoded data, the moving picturedecoding method including: a step A of decoding the encoded data toobtain a chrominance residual signal; a step B of setting a decodedluminance component of a prediction target block to the same number ofsamples as that of the chrominance component corresponding to thedecoded luminance component of the prediction target block andgenerating a luminance reference signal; a step C of specifying pixelsof luminance having the minimum and maximum pixel values of the decodedluminance component adjacent to the decoded luminance component of theprediction target block, respectively, outputting luminance pixel valuesobtained from the specified pixels of luminance, and outputtingchrominance pixel values obtained from pixels of pigment correspondingto the pixels of luminance; a step D of deriving a linear predictionparameter from the luminance pixel value, the chrominance pixel value,and a linear prediction model; a step E of obtaining a chrominanceprediction signal by applying the linear prediction model based on thelinear prediction parameter to the luminance reference signal; a step Fof adding the chrominance prediction signal and the chrominance residualsignal to generate a reconstructed chrominance signal; and a step G ofsetting an upper limit for a magnitude of the linear predictionparameter, wherein in the step C, the decoded luminance componentadjacent to the decoded luminance component of the prediction targetblock is set to the same number of samples as that of the chrominancecomponent corresponding to the decoded luminance component of theprediction target block, and the pixels having the minimum and maximumvalues of the luminance component are specified respectively.

The third aspect of the present invention is summarized as a programused in a moving picture decoding device configured to decode encodeddata, the program causes a computer to execute: a step A of decoding theencoded data to obtain a chrominance residual signal; a step B ofsetting a decoded luminance component of a prediction target block tothe same number of samples as that of the chrominance componentcorresponding to the decoded luminance component of the predictiontarget block and generating a luminance reference signal; a step C ofspecifying pixels of luminance having the minimum and maximum pixelvalues of the decoded luminance component adjacent to the decodedluminance component of the prediction target block, respectively,outputting luminance pixel values obtained from the specified pixels ofluminance, and outputting chrominance pixel values obtained from pixelsof pigment corresponding to the pixels of luminance; a step D ofderiving a linear prediction parameter from the luminance pixel value,the chrominance pixel value, and a linear prediction model; a step E ofobtaining a chrominance prediction signal by applying the linearprediction model based on the linear prediction parameter to theluminance reference signal; a step F of adding the chrominanceprediction signal and the chrominance residual signal to generate areconstructed chrominance signal; and a step G of setting an upper limitfor a magnitude of the linear prediction parameter, wherein in the stepC, the decoded luminance component adjacent to the decoded luminancecomponent of the prediction target block is set to the same number ofsamples as that of the chrominance component corresponding to thedecoded luminance component of the prediction target block, and thepixels having the minimum and maximum values of the luminance componentare specified respectively.

According to the present invention, it is possible to provide a movingpicture decoding device, a moving picture encoding device, a movingpicture processing system, a moving picture decoding method, and aprogram capable of reducing a precision (number of bits) of a lookuptable and determining the maximum value of an absolute value of aprediction coefficient to reduce a required calculation precision(number of bits required for calculation) to the same degree as thecalculation precision of an interpolation filter.

In addition, it is possible to provide a moving picture decoding device,a moving picture encoding device, a moving picture processing system, amoving picture decoding method, and a program capable of determiningpixels whose luminance becomes the minimum value and the maximum valuewithout smoothing and completely reducing a smoothing operation eventhough the number of comparisons is doubled.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an example of a configuration of amoving picture processing system 1 according to an embodiment.

FIG. 2 is a diagram illustrating an example of functional blocks of amoving picture encoding device 10 according to an embodiment.

FIG. 3 is a diagram illustrating an example of a function for performingchrominance intra prediction in an intra prediction unit 12 of themoving picture encoding device 10 according to an embodiment.

FIG. 4 is a diagram illustrating an example of functional blocks of amoving picture decoding device 30 according to an embodiment.

FIG. 5 is a flowchart illustrating an example of an operation of themoving picture decoding device 30 according to an embodiment.

FIG. 6 is a diagram for describing a conventional technique.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be described withreference to the drawings. Note that the components in the followingembodiments can be appropriately replaced with existing components andthe like, and various variations including combinations with otherexisting components are possible. Therefore, the description of thefollowing embodiments does not limit the contents of the inventiondescribed in the claims.

First Embodiment

FIG. 1 is a diagram illustrating an example of a configuration of amoving picture processing system 1 according to a first embodiment ofthe present invention.

As illustrated in FIG. 1, a moving picture processing system 1 accordingto the present embodiment includes a moving picture encoding device 10that encodes a moving picture to generate encoded data, and a movingpicture decoding device 30 that decodes the encoded data generated bythe moving picture encoding device 10. The moving picture encodingdevice 10 and the moving picture decoding device 30 are configured totransmit and receive the above-described encoded data via, for example,a transmission path.

FIG. 2 is a diagram illustrating an example of functional blocks of themoving picture encoding device 10 according to the present embodiment.

As illustrated in FIG. 2, the moving picture encoding device 10according to the present embodiment includes an inter prediction unit11, an intra prediction unit 12, a transform/quantization unit 13, anentropy encoding unit 14, an inverse transform/inverse quantization unit15, a subtraction unit 16, an addition unit 17, an in-loop filter unit18, and a frame buffer unit 19.

The inter prediction unit 11 is configured to receive an input image anda locally decoded image after filtering to be described later suppliedfrom the frame buffer unit 19. The inter prediction unit 11 isconfigured to perform inter prediction using the input image and thelocally decoded image after filtering to generate and output an interpredicted image.

The intra prediction unit 12 is configured to receive an input image anda locally decoded image before filtering (reconstructed chrominancesignal) to be described later. The intra prediction unit 12 isconfigured to perform intra prediction using the input image and thelocally decoded image before filtering to generate and output an intrapredicted image.

Here, the intra predicted image includes a luminance prediction signaland a chrominance prediction signal. Note that the locally decoded imagebefore filtering includes a luminance component and a chrominancecomponent.

The transform/quantization unit 13 is configured to perform orthogonaltransform processing on an input residual signal, perform quantizationprocessing on a transform coefficient obtained by the orthogonaltransform processing, and output a quantized level value.

The entropy encoding unit 14 is configured to receive the quantizedlevel value, a transform unit (TU) size, and a transform size. Theentropy encoding unit 14 is configured to entropy-encode the inputsignal and output the entropy-encoded signal as encoded data.

The inverse transform/inverse quantization unit 15 is configured toreceive the quantized level value. The inverse transform/inversequantization unit 15 is configured to perform inverse quantizationprocessing on the quantized level value, perform inverse orthogonaltransform processing on a transform coefficient obtained by the inversequantization processing, and output an inverse orthogonal transformedresidual signal.

The subtraction unit 16 is configured to receive the input image and theintra predicted image or the inter predicted image, and output aresidual signal that is a difference between the two.

The addition unit 17 is configured to receive the residual signal andthe intra predicted image or the inter predicted image, and output thelocally decoded image before filtering obtained by adding the two.

The in-loop filter unit 18 is configured to receive the locally decodedimage before filtering. Here, the locally decoded image before filteringis a signal obtained by adding the prediction image and the inverseorthogonal transformed residual signal.

The in-loop filter unit 18 is configured to perform filtering processingsuch as a deblocking filter on the locally decoded image beforefiltering, to generate and output the locally decoded image afterfiltering.

The frame buffer unit 19 is configured to accumulate the locally decodedimage after filtering and appropriately supply the locally decoded imageafter filtering to the inter prediction unit 11 as the locally decodedimage after filtering.

FIG. 3 is a diagram illustrating an example of a function for predictinga chrominance component from a reconstructed luminance component(decoded luminance component of a prediction target block and decodedluminance component adjacent to the decoded luminance component of theprediction target block) in the intra prediction unit 12 of the movingpicture encoding device 10 according to the present embodiment.

As illustrated in FIG. 3, the function of performing the chrominanceintra prediction includes a transform unit 12 a, a specification unit 12b, a derivation unit 12 c, a chrominance linear prediction unit 12 d,and an addition unit 12 e. Here, whether or not to apply the chrominanceintra prediction is determined by a chrominance intra prediction modesubjected to the entropy decoding.

The transform unit 12 a is configured to set the decoded luminancecomponent of the prediction target block (included in the locallydecoded image before filtering) to the same number of samples as thatthe chrominance components corresponding to the decoded luminancecomponent of the prediction target block and output a luminancereference signal. Here, a 6-tap filter may be applied to the transformof the number of samples.

In addition, the decoded luminance component of the prediction targetblock is input from the addition unit 17 to the transform unit 12 a.

The specification unit 12 b is configured to specify pixels of luminancehaving the minimum and maximum pixel values of the decoded luminancecomponent (included in the locally decoded image before filtering)adjacent to the decoded luminance component of the prediction targetblock, respectively. In addition, the specification unit 12 b isconfigured to output luminance pixel values of the specified pixels ofluminance and chrominance pixel values of pixels of chrominancecorresponding to the specified pixels of luminance.

Here, when the number of samples of the luminance component and thenumber of samples of the chrominance component are different, the pixelof the luminance and the pixel of the chrominance may not correspondone-to-one. However, since it can be assumed that the number of samplesof the luminance component is larger than the number of samples of thechrominance component, the pixel of the chrominance corresponding to thepixel of the luminance can be uniquely determined.

The specification unit 12 b receives, from the addition unit 17, adecoded luminance component adjacent to the decoded luminance componentof the prediction target block and a decoded chrominance componentadjacent to the decoded luminance component of the prediction targetblock.

The derivation unit 12 c is configured to derive a linear predictionparameter for inputting the minimum and maximum pixel values of theluminance component, the pixel values of the corresponding chrominance,and a linear prediction model.

The chrominance linear prediction unit 12 d is configured to output achrominance prediction signal by applying the linear prediction modelbased on the linear prediction parameter to the luminance referencesignal.

The addition unit 12 e is configured to generate a reconstructedchrominance signal by adding the chrominance prediction signal and thechrominance residual signal.

FIG. 4 is a diagram illustrating an example of functional blocks of themoving picture decoding device 30 according to the present embodiment.

As illustrated in FIG. 4, the moving picture decoding device 30according to the present embodiment includes an entropy decoding unit31, an inverse transform/inverse quantization unit 32, an interprediction unit 33, an intra prediction unit 34, an addition unit 35, anin-loop filter unit 36, and a frame buffer unit 37.

The entropy decoding unit 31 is configured to receive encoded data. Theentropy decoding unit 31 is configured to perform entropy decoding ofthe encoded data, and derive and output a quantization coefficient levelvalue and a chrominance intra prediction mode generated by the movingpicture encoding device 10.

The inverse transform/inverse quantization unit 32 is configured toreceive the quantization coefficient level value. The inversetransform/inverse quantization unit 32 is configured to perform inversequantization processing on the quantization coefficient level value,perform inverse orthogonal transform processing on a result obtained bythe inverse quantization processing, and output a residual signal(including a luminance residual signal and a chrominance residualsignal).

The inter prediction unit 33 is configured to receive a locally decodedimage after filtering to be described later, supplied from the framebuffer unit 37. The inter prediction unit 33 is configured to performinter prediction using the locally decoded image after filtering togenerate and output an inter predicted image.

The intra prediction unit 34 is configured to receive a locally decodedimage before filtering. Here, the locally decoded image before filteringis a signal obtained by adding the residual signal and the predictionimage, and the prediction image is a prediction image calculated by aprediction method that is expected to have the highest encodingperformance obtained by entropy decoding, among the inter predictedimage and the intra predicted image.

Note that the intra prediction unit 34 is configured to perform intraprediction using the locally decoded image before filtering to generateand output the intra predicted image. The addition unit 35 is configuredto receive the residual signal and the intra predicted image or theinter predicted image, and output a locally decoded image beforefiltering obtained by adding the two.

The in-loop filter unit 36 is configured to receive the locally decodedimage before filtering. The in-loop filter unit 36 is configured toapply an in-loop filter such as a deblocking filter to the locallydecoded image before filtering and output the locally decoded imageafter filtering.

The frame buffer unit 37 is configured to accumulate the locally decodedimage after filtering, appropriately supply the locally decoded imageafter filtering to the inter prediction unit 33 as the locally decodedimage after filtering, and output the locally decoded image afterfiltering as the decoded image.

FIG. 3 is a diagram illustrating an example of a function for predictinga chrominance component from a reconstructed luminance component in theintra prediction unit 34 of the moving picture decoding device 30according to the present embodiment.

As illustrated in FIG. 3, the function of performing the chrominanceintra prediction includes a transform unit 34 a, a specification unit 34b, a derivation unit 34 c, a chrominance linear prediction unit 34 d,and an addition unit 34 e. Note that each function is the same as thefunction in the moving picture encoding device 10, and thus detaileddescription is omitted.

Hereinafter, an operation of predicting a chrominance component from areconstructed luminance component in the moving picture decoding device30 according to the present embodiment will be described with referenceto FIG. 5.

As illustrated in FIG. 5, the moving picture decoding device 30 decodesthe encoded data in step S101, and acquires the chrominance intraprediction mode and the chrominance residual signal in step S102.

In step S103, the moving picture decoding device 30 sets the decodedluminance component of the prediction target block to the same number ofsamples as that of the chrominance components corresponding to thedecoded luminance component of the prediction target block and generatesa luminance reference signal.

In step S104, the moving picture decoding device 30 specifies the pixelsof luminance having the minimum and maximum pixel values of the decodedluminance component adjacent to the decoded luminance component of theprediction target block, respectively, and outputs luminance pixelvalues of the specified pixels of luminance and chrominance pixel valuesof pixels of pigment corresponding to the pixels of luminance.

In step S105, the moving picture decoding device 30 derives a linearprediction parameter from the luminance pixel value, the chrominancepixel value, and a linear prediction model.

In step S106, the moving picture decoding device 30 acquires achrominance prediction signal by applying the linear prediction modelbased on the linear prediction parameter to the luminance referencesignal.

In step S107, the moving picture decoding device 30 generates areconstructed chrominance signal by adding the chrominance predictionsignal and the chrominance residual signal.

According to the moving picture encoding device 10 and the movingpicture decoding device 30 according to the present embodiment, sincethe specification unit 12 b/34 b specifies the minimum and maximum pixelvalues without smoothing adjacent decoded luminance components, thenumber of shift operations can be reduced, and since the adjacentdecoded luminance components are specified without applying theconventional 6-tap filter at all, the number of addition operations canbe further reduced.

Second Embodiment

Hereinafter, the moving picture encoding device 10 and the movingpicture decoding device 30 according to a second embodiment of thepresent invention will be described focusing on differences from themoving picture encoding device 10 and the moving picture decoding device30 according to the above-described first embodiment.

In the present embodiment, the derivation unit 12 c/34 c is configuredto apply shift processing to the number of bits of the linear predictionparameter to be output, in order to make the same number of bits as thatof the interpolation operation in a motion compensation prediction inthe inter prediction unit 33 of the moving picture decoding device 30.

Specifically, the derivation unit 12 c/34 c is configured to reduce thenumber of bits in a fixed-point representation of the lookup table whenperforming division by the difference between the maximum value and theminimum value of the luminance value using the lookup table. Forexample, the number of bits of the lookup table value may be 8 bits.

In addition, the derivation unit 12 c/34 c divides the differencebetween the maximum value and the minimum value of the chrominancevalues, and clips the maximum value of the difference to a predeterminedrange. For example, the derivation unit 12 c/34 c may be from −256 to255, which is a range of a signed 9-bit integer.

According to the moving picture encoding device 10 and the movingpicture decoding device 30 according to the present embodiment, sincethe specification unit 12 b/34 b specifies the minimum and maximum pixelvalues without smoothing adjacent decoded luminance components, thenumber of shift operations can be reduced, and since the adjacentdecoded luminance components are specified without applying theconventional 6-tap filter at all, the number of addition operations canbe further reduced. Further, similarly to the interpolation operation inthe inter prediction, the number of bits of a multiplier becomes 17bits, and the design cost of the multiplier can be reduced.

Third Embodiment

Hereinafter, the moving picture encoding device 10 and the movingpicture decoding device 30 according to a third embodiment of thepresent invention will be described focusing on differences from themoving picture encoding device 10 and the moving picture decoding device30 according to the above-described first and second embodiment.

In the present embodiment, the derivation unit 12 c/34 c is configuredto set an upper limit for the magnitude of the linear predictionparameter.

For example, the derivation unit 12 c/34 c may be configured to apply aclip operation and a shift operation to the linear prediction parameter.

For example, the linear prediction parameter is composed of a sign 1bit, an integer part 3 bits, and a fixed point part 8 bits so as to be asigned 12-bit fixed point. As a result, the chrominance linearprediction units 12 d and 33 d may be configured such that the number ofbits of a product-sum operation unit is 17 bits, similarly to the numberof bits of a product-sum operation unit of the interpolation operation.

In addition, the linear prediction parameter may be configured to be asigned 7-bit fixed point. As a result, the chrominance linear predictionunits 12 d and 33 d may be configured such that the number of bits ofthe multiplier is 17 bits, similarly to the number of bits of themultiplier for the interpolation operation.

In addition, the linear prediction parameter may be configured to be asigned 7-bit floating point. As a result, the chrominance linearprediction units 12 d and 33 d may be configured such that the number ofbits of the multiplier is a combination of 17 bits and the shiftoperation, similarly to the number of bits of the multiplier for theinterpolation operation.

According to the moving picture encoding device 10 and the movingpicture decoding device 30 according to the present embodiment, evenwhen the fluctuation in the luminance component is small, it is possibleto suppress the chrominance signal from being linearly predicted beyondthe range of the input signal because the linear prediction parameter issuppressed to a certain value or less.

Fourth Embodiment

Hereinafter, the moving picture encoding device 10 and the movingpicture decoding device 30 according to a fourth embodiment of thepresent invention will be described focusing on differences from themoving picture encoding device 10 and the moving picture decoding device30 according to the above-described first to third embodiments.

In the present embodiment, the specification unit 12 b/34 b isconfigured to set the decoded luminance component to the same number ofsamples as that of the chrominance components corresponding to thedecoded luminance component and generate the luminance reference signal.

Specifically, the specification unit 12 b/34 b may be configured toapply a horizontal 3-tap smoothing filter to an upper referenceluminance component and apply a vertical 2-tap smoothing filter to aleft adjacent reference luminance component.

According to the moving picture encoding device 10 and the movingpicture decoding device 30 according to the present embodiment, noise inadjacent reference luminance components can be suppressed, andprediction precision can be improved.

What is claimed is:
 1. A moving picture decoder configured to decodeencoded data, comprising a memory comprising programmed instructionsstored in the memory and a processor configured to be capable ofexecuting the programmed instructions stored in the memory to: decodethe encoded data to obtain a chrominance residual signal; set a decodedluminance component of a prediction target block to a same number ofsamples as that of a chrominance component corresponding to the decodedluminance component of the prediction target block, and generate aluminance reference signal; specify pixels of luminance having a minimumand maximum pixel values of the decoded luminance component adjacent tothe decoded luminance component of the prediction target block,respectively, output luminance pixel values obtained from the specifiedpixels of luminance, and output chrominance pixel values obtained frompixels of pigment corresponding to the pixels of luminance; derive alinear prediction parameter from the luminance pixel value, thechrominance pixel value, and a linear prediction model; obtain achrominance prediction signal by applying the linear prediction modelbased on the linear prediction parameter to the luminance referencesignal; and add the chrominance prediction signal and the chrominanceresidual signal to generate a reconstructed chrominance signal; whereina maximum value of a difference between a maximum value and a minimumvalue of the chrominance pixel value is clipped to a predeterminedrange, the decoded luminance component adjacent to the decoded luminancecomponent of the prediction target block is set to the same number ofsamples as that of the chrominance component corresponding to thedecoded luminance component of the prediction target block, the pixelshaving the minimum and maximum values of a luminance component arespecified, respectively, and the linear prediction parameter beingderived by look up table which represents the division processing arespecified, respectively.
 2. A moving picture decoding method fordecoding encoded data, the moving picture decoding method comprising: astep A of decoding the encoded data to obtain a chrominance residualsignal; a step B of setting a decoded luminance component of aprediction target block to a same number of samples as that of achrominance component corresponding to the decoded luminance componentof the prediction target block and generating a luminance referencesignal; a step C of specifying pixels of luminance having a minimum andmaximum pixel values of the decoded luminance component adjacent to thedecoded luminance component of the prediction target block,respectively, outputting luminance pixel values obtained from thespecified pixels of luminance, and outputting chrominance pixel valuesobtained from pixels of pigment corresponding to the pixels ofluminance; a step D of deriving a linear prediction parameter from theluminance pixel value, the chrominance pixel value, and a linearprediction model; a step E of obtaining a chrominance prediction signalby applying the linear prediction model based on the linear predictionparameter to the luminance reference signal; a step F of adding thechrominance prediction signal and the chrominance residual signal togenerate a reconstructed chrominance signal; and a step G of clipping amaximum value of a difference between a maximum value and a minimumvalue of the chrominance pixel value to a predetermined range, whereinin the step C, the decoded luminance component adjacent to the decodedluminance component of the prediction target block is set to the samenumber of samples as that of the chrominance component corresponding tothe decoded luminance component of the prediction target block, thepixels having the minimum and maximum values of a luminance componentare specified, respectively, and the linear prediction parameter beingderived by look up table which represents the division processing arespecified, respectively.
 3. A non-transitory computer readable mediumhaving stored thereon instructions for decoding encoded data, comprisingmachine executable code which when executed by at least one machinecauses the machine to perform: a step A of decoding the encoded data toobtain a chrominance residual signal; a step B of setting a decodedluminance component of a prediction target block to a same number ofsamples as that of a chrominance component corresponding to the decodedluminance component of the prediction target block and generating aluminance reference signal; a step C of specifying pixels of luminancehaving a minimum and maximum pixel values of the decoded luminancecomponent adjacent to the decoded luminance component of the predictiontarget block, respectively, outputting luminance pixel values obtainedfrom the specified pixels of luminance, and outputting chrominance pixelvalues obtained from pixels of pigment corresponding to the pixels ofluminance; a step D of deriving a linear prediction parameter from theluminance pixel value, the chrominance pixel value, and a linearprediction model; a step E of obtaining a chrominance prediction signalby applying the linear prediction model based on the linear predictionparameter to the luminance reference signal; a step F of adding thechrominance prediction signal and the chrominance residual signal togenerate a reconstructed chrominance signal; and a step G of clipping amaximum value of a difference between a maximum value and a minimumvalue of the chrominance pixel value to a predetermined range, whereinin the step C, the decoded luminance component adjacent to the decodedluminance component of the prediction target block is set to the samenumber of samples as that of the chrominance component corresponding tothe decoded luminance component of the prediction target block, thepixels having the minimum and maximum values of a luminance componentare specified, respectively, and the linear prediction parameter beingderived by look up table which represents the division processing arespecified, respectively.